Histological study of rat tissues following injection of an oxyphoretic emulsion: perfluorocompounds

Abstract

Perfluorocompounds are promising substances in medicine due to their ability to dissolve large amounts of oxygen, and many experimental and clinical studies have been carried out since 1966. We tested different emulsions of a mixture of PFC (RM 101 Enichem Synthesis. Italy: 82.1% perfluorobutylfurane 7.5% perfluoropropylpyrane 7.4% others) in rats, in both perfused organs and in vivo following a single intravenous injection, looking at the morphological alterations of various tissues under optical microscopy. According to previous studies, PFC particles can be identified histologically as lipid-like empty spaces. Our results can be summarized as follows: 1. Due to their diameter (about 2 microns) PFC particles can freely circulate in the vessels and capillaries, where they can be identified in the blood in the first week, and mostly after 24–72 hours. 2. PFC are immediately captured by reticuloendothelial cells, with significant appearance in the spleen, lymph nodes, liver and lung, and even by non RES cells, i.e. hepatocytes. Conversely, other tissues do not show significant changes: heart, pancreas, kidney… Cellular uptake increases during the first few days up to a week following intravenous injection, and tends to disappear in about one month. 3. Lungs show an impressive alteration, with many macrophages engulfed by PFC particles in the alveolar septa and a subsequent ‘pseudoluminization’ pattern possibly due to the release of PFC in gaseous form. 4. Neither cellular necrosis nor inflammatory reaction nor persistent alterations have been observed, confirming the good general tolerance of rat tissues to PFC. 5. Others studies are necessary to obtain an ideal emulsion as blood substitute, particularly for repeated injection. PFC appear promising substances in preserving some organs for transplantation.